In general, among technologies to form various thin films on a substrate or a wafer, a CVD (Chemical Vapor Deposition) scheme has been extensively used. The CVD scheme results in a chemical reaction. According to the CVD scheme, a semiconductor thin film or an insulating layer is formed on a wafer surface by using the chemical reaction of a source material.
The CVD scheme and the CVD device have been spotlighted as an important thin film forming technology due to the fineness of the semiconductor device and the development of high-power and high-efficiency LED. Recently, the CVD scheme has been used to deposit various thin films, such as a silicon layer, an oxide layer, a silicon nitride layer, a silicon oxynitride layer, or a tungsten layer, on a wafer.
Hereinafter, a silicon carbide epitaxial deposition apparatus according to the related art will be described.
According to the related art, reactive gas is supplied to a deposition apparatus through a reactive gas feeding part, and the reactive gas inflowing into the deposition apparatus is introduced into a susceptor. Thereafter, as air flows through a space between upper and lower plates of the susceptor, the reactive gas introduced into the susceptor is applied to the top surface of a wafer so that a deposition process can be performed.
In this case, the wafer may be placed on the lower plate of the susceptor, or the wafer may be placed on a wafer holder after the wafer holder has been placed on the lower plate of the susceptor, so that an epitaxial layer can be grown by using the reactive gas introduced into the susceptor.
In other words, since the wafer cannot adjust the reactive gas introduced into the susceptor, the diffusion of the reactive gas cannot be smoothly achieved. In addition, since the epitaxial layer is grown upward on the top surface of the wafer, the wafer may be defected by down pull particles.
Therefore, there is required a deposition apparatus equipped with a wafer holder capable of growing an epitaxial layer on a lower surface of the wafer while smoothly diffusing reactive gas, which has been introduced into the susceptor, to the wafer.